Remove custom matrix from PS2AVRGB boards (#7396)

* Remove custom matrix from PS2AVRGB boards

* Add custom backlight.c to SRC for bminiex, for now

* Add missing DIODE_DIRECTIONs

keyboards/mechmini/v1/v1.c

@@ -16,13 +16,3 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 #include "v1.h"
-
-void matrix_init_kb(void) { matrix_init_user(); }
-
-__attribute__ ((weak))
-void matrix_init_user(void) {}
-
-void matrix_scan_kb(void) { matrix_scan_user(); }
-
-__attribute__ ((weak))
-void matrix_scan_user(void) {}